JPH0547144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data transmission system within a data communication network in which data is accumulated in units of fixed blocks and data is transmitted in units of accumulated blocks.

[Prior Art] FIG. 6 shows a normal data transmission operation in a conventional data transmission system, and FIG. 7 shows an operation when data is lost within a network. In FIG. 6, 1a,
Reference numerals 1b and 1d represent packet switching equipment constituting the packet switching network, 2 a data storage buffer in the packet switching equipment 1a, 3a, 3b, 3c, and 3d data randomly generated in the packet switching equipment 1a, and 30 and 32 data that are generated randomly in the packet switching equipment 1a. A packet 31 transmits transmission data to the exchange 1d, a response packet 31 to the packet 30 in the packet exchange 1d, and response data 6a and 6b indicating that data 3a and 3b have been received.

In FIG. 7, 33a is a packet that transmits data 3a and 3b, 33b is a packet that is retransmitted because packet 33a is lost in the network,
4 is a response packet to packet 33b, 35
is a packet transmitted at the timing following packet 33a.

Next, the operation will be explained. The operation of normal data transmission will be explained with reference to FIG. The packet switch 1a transmits the generated data 3
A and 3b are converted into a packet 30 and sent to the packet exchange 1d. The packet 30 is relayed by the packet switch 1b and transmitted to the packet switch 1d. Packet switch 1d sends packet 30
and processes the data 3a, 3b, and at the same time transmits a response packet 31 containing response data 6a, 6b indicating that the data 3a, 3b have been received to the packet exchange 1a. The response packet 31 is relayed by the packet switch 1b and transmitted to the packet switch 1a. Packet switch 1
a receives the response packet 31 and sends the response data 6
After confirming that the data 3a and 3b have been transmitted to the packet switch 1d from a and 6b, the data 3a and
The memory area used for 3b is released to the data storage buffer 2. And packet switch 1
a is the data 3 generated after the transmission of packet 30 after a certain period of time has elapsed since the transmission of packet 30.
The packets 32 and 3d are converted into packets 32 and transmitted to the packet exchange 1d. Thereafter, processing is performed in the same manner as above.

Next, the operation when transmitted data is lost within the network will be explained with reference to FIG. The packet switch 1a packetizes the generated data 3a and 3b into a packet 33a, and sends the data to the packet switch 1d.
Send to. However, if the packet switch 1a does not receive a response packet from the packet switch 1d within the response timeout time (Tout), it assumes that the packet 33a has been lost within the network and returns the data 3 as the same as the packet 33a.
A retransmission packet 33b is generated by packetizing a and 3b, and is retransmitted. Then, the packet switch 1d
At the time when the response packet 34 is received from the response data 6a and 6b, the area for the data 3a and 3b is released to the data storage buffer 2 based on the response data 6a and 6b. and,
After a certain period of time has elapsed since the transmission of the packet 33a, the data 3 generated after the transmission of the packet 33a is
c and 3d into packets to generate a packet 35 and send it to the packet exchange 1d.

[Problem that the invention seeks to solve]

Since the conventional data transmission method is performed as described above, as shown in FIG.
When generating a retransmitted packet 33b due to the disappearance of the data 33b, the data 3c, 3
Even if d occurs, the transmission of these data 3c and 3d has to wait until the next transmission timing, resulting in a problem that the transmission of information is delayed.

Furthermore, at the next transmission timing, even if there is only data 3c to be transmitted, it must be transmitted as one packet, and the packet transmission and reception processing in the packet exchanges 1a and 1d,
There was a problem in that the load on the relay processing in the packet switch 1b increased.

This invention was made to solve the above-mentioned problems, and makes it possible to transmit newly generated transmission data at an earlier timing by utilizing the timing of packet retransmission due to causes such as packet loss within the network. Another object of the present invention is to obtain a data transmission system that can reduce the load on a packet switching network.

[Means for solving problems]

The data transmission method according to the present invention is capable of retransmitting a packet due to reasons such as packet loss within a network, in addition to the data held by the lost packet, data at a newly generated data retransmission point after the transmission of the lost packet is transmitted. A playback packet including the data is generated and retransmitted.

[Effect]

The data transmission method in this invention regenerates newly generated data at a faster timing by regenerating retransmitted packets based on the data waiting for transmission at the time of packet retransmission in addition to the retransmitted data that was previously attempted to be transmitted. It also increases the amount of data contained in one packet.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a data transmission system according to an embodiment of the present invention.
a and 1b are packet switches forming a packet switching network; 1c is a network control device having a function of collecting and managing data generated in each packet switch in the network;
2 is a data storage buffer for storing data generated in the packet exchange 1a, 3a, 3b,
3c and 3d are data randomly generated in the packet switch 1a, 4a is a packet that transmits data 3a and 3b to the network control device 1c at a certain timing, and 4b is a packet that the packet switch 1a judges to be lost within the network. When doing so, in addition to data 3a and 3b, data 1c and 1d
5 is a response packet that returns a response to the network control device 1c receiving the retransmitted packet 4b from the packet switch 1a. 6a, 6b, 6c, and 6d are data 3a, 3b. , 3c, and 3d are received.

Next, the operation of the above embodiment will be explained. At the packet transmission timing, the packet switch 1a generates a packet 4a for transmitting the data 3a, 3b that has already been generated, and transmits it to the network control device 1c. However, in the packet switch 1a,
Network control device 1 within response timeout time Tout
If no response packet is received from c, it is determined that the packet 4a has been lost within the network, and a retransmitted packet 4b is generated. At that time, packet 4
In addition to data 3a and 3b contained in a,
Data 3 generated after generation and transmission of packet 4a
Generate retransmission packet 4b which also includes packets c and 3d,
It is transmitted to the network control device 1c. Then, the packet exchange 1a receives the response packet 5 from the network control device 1c, confirms that the data 3a, 3b, 3c, and 3d have been transmitted from the response data 6a, 6b, 6c, and 6d, and transmits the data 3a, 3b, 3c and 3d are released to the data storage buffer 2. Furthermore, if no data is generated from the time of retransmission of the retransmitted packet 4b until the next packet transmission timing, there is no need to transmit a packet at the next packet transmission timing.

FIG. 2 shows the data structure in a packet switch. The generated data 8a, 8b, 8c, and 8d form a queue 7, with the oldest data 8a, second oldest data 8b, third oldest data 8c, and the newest data 8d at the end. be.
Furthermore, newly generated data 9 acquires an area from the data storage buffer 2 and is added to the tail of the queue 7. Furthermore, data whose transmission has been confirmed by receiving a response packet is taken out from the queue 7 and released into the data storage buffer 2.

FIG. 3 shows a flowchart of packet generation and transmission in a packet switch. When generating and transmitting a packet, it is checked in step 10 whether or not there is data in the queue 7. If there is no data in the queue 7, the process ends without generating or transmitting a packet. If there is data, a serial number for data identification is given to the data in order from the head of the queue 7 in step 11, and the data is added to the transmission packet in step 12. Furthermore, it is confirmed in step 13 that there is next data in queue 7, and in step 14
If it is confirmed that there is room to add data to the transmitted packet, the process of block 15 is repeated. If there is no more data in the queue 7 or if there is no room to add data to the transmission packet, the transmission packet generated in step 16 is transmitted and the process is terminated. Following this flow, it is possible to process both packet transmission and packet retransmission. However, in step 11 of assigning an identification number to data when retransmitting a packet, a new identification number is not assigned to data that already has an identification number in order to avoid double assignment of an identification number.

FIG. 4 shows a flowchart of processing when a response packet is received in a packet exchange. In step 17, the identification number of the data confirmed to have been transmitted is confirmed from the response data shown in the response packet, and in step 18, it is determined whether the data has been released into the data storage buffer. If the data area has not yet been released, the data area is released in step 19, and it is determined in step 20 whether or not there is next response data in the response packet. If there is response data, the process of block 21 is repeated; if there is no response data, the process ends.

FIG. 5 shows a flowchart of processing at the time of packet reception in the network control device. In step 22, response data is generated based on the data indicated in the received packet, a response packet is created, and in step 23, the response packet is transmitted. Furthermore, in step 24, the identification number of the received data is recognized,
In step 25, the last last processed data is compared with the identification number to determine whether the data has been processed or not, and in step 26, if it is unprocessed, it is processed. Furthermore, if it is confirmed in step 27 that the next data exists, the process in block 28 is repeated, and if there is no next data, the identification number of the last data processed is recorded in step 29, and the process ends. do.

〔Effect of the invention〕

As described above, according to the present invention, if response data indicating packet delivery confirmation is not received within a predetermined time after transmitting a packet, data newly generated after transmitting the packet and data included in the packet are transmitted. Since the configuration is configured to regenerate new packets from the data and transmit the regenerated packets, newly generated data can be transmitted at a fast timing, and even when the transmitted packets are lost. Even if response data is lost, the lost packet can be retransmitted, resulting in highly reliable data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the operation of a data transmission system according to an embodiment of the invention, FIG. 2 is an explanatory diagram showing the data structure inside a packet switch according to an embodiment of the invention, and FIG. FIG. 4 is a flowchart showing packet generation and transmission processing in a data transmission side packet switch according to an embodiment of the invention; FIG. 4 is a flowchart of response packet reception processing in a data transmission side packet switch according to an embodiment of the invention; FIG. 5 is a flowchart of packet reception processing, response packet generation, and transmission processing in a network control device on the data receiving side according to an embodiment of the present invention, and FIG. 6 is a normal data transmission operation in a conventional data transmission system. FIG. 7 is a block diagram showing the operation when data is lost within the network in a conventional data transmission system. 1a and 1b are packet switches, 1c is a network control device, 2 is a data storage buffer, 3a to 3b are data, 4a is a packet, 4b is a retransmission packet, 5
is a response packet, and 6a to 6d are response data. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 In a data transmission system within a data communication network that accumulates data in predetermined block units to generate packets and transmits the packets, after transmitting the packets, the packet delivery confirmation is indicated within a predetermined time. If response data is not received, a new packet is regenerated from data newly generated after transmitting the packet and data included in the packet, and the regenerated packet is transmitted. data transmission method.